分类： 地球科学 >> 地理学 提交时间： 2024-02-21 合作期刊: 《干旱区科学》
摘要： Land use and cover change (LUCC) is the most direct manifestation of the interaction between anthropological activities and the natural environment on Earth's surface, with significant impacts on the environment and social economy. Rapid economic development and climate change have resulted in significant changes in land use and cover. The Shiyang River Basin, located in the eastern part of the Hexi Corridor in China, has undergone significant climate change and LUCC over the past few decades. In this study, we used the random forest classification to obtain the land use and cover datasets of the Shiyang River Basin in 1991, 1995, 2000, 2005, 2010, 2015, and 2020 based on Landsat images. We validated the land use and cover data in 2015 from the random forest classification results (this study), the high-resolution dataset of annual global land cover from 2000 to 2015 (AGLC-2000-2015), the global 30 m land cover classification with a fine classification system (GLC_FCS30), and the first Landsat-derived annual China Land Cover Dataset (CLCD) against ground-truth classification results to evaluate the accuracy of the classification results in this study. Furthermore, we explored and compared the spatiotemporal patterns of LUCC in the upper, middle, and lower reaches of the Shiyang River Basin over the past 30 years, and employed the random forest importance ranking method to analyze the influencing factors of LUCC based on natural (evapotranspiration, precipitation, temperature, and surface soil moisture) and anthropogenic (nighttime light, gross domestic product (GDP), and population) factors. The results indicated that the random forest classification results for land use and cover in the Shiyang River Basin in 2015 outperformed the AGLC-2000-2015, GLC_FCS30, and CLCD datasets in both overall and partial validations. Moreover, the classification results in this study exhibited a high level of agreement with the ground truth features. From 1991 to 2020, the area of bare land exhibited a decreasing trend, with changes primarily occurring in the middle and lower reaches of the basin. The area of grassland initially decreased and then increased, with changes occurring mainly in the upper and middle reaches of the basin. In contrast, the area of cropland initially increased and then decreased, with changes occurring in the middle and lower reaches. The LUCC was influenced by both natural and anthropogenic factors. Climatic factors and population contributed significantly to LUCC, and the importance values of evapotranspiration, precipitation, temperature, and population were 22.12%, 32.41%, 21.89%, and 19.65%, respectively. Moreover, policy interventions also played an important role. Land use and cover in the Shiyang River Basin exhibited fluctuating changes over the past 30 years, with the ecological environment improving in the last 10 years. This suggests that governance efforts in the study area have had some effects, and the government can continue to move in this direction in the future. The findings can provide crucial insights for related research and regional sustainable development in the Shiyang River Basin and other similar arid and semi-arid areas.
分类： 地球科学 >> 地理学 提交时间： 2023-12-20 合作期刊: 《干旱区科学》
摘要： The Ili River Delta (IRD) is an ecological security barrier for the Lake Balkhash and an important water conservation area in Central Asia. In this study, we selected the IRD as a typical research area, and simulated the water yield and water conservation from 1975 to 2020 using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. We further analyzed the temporal and spatial variations in the water yield and water conservation in the IRD from 1975 to 2020, and investigated the main driving factors (precipitation, potential evapotranspiration, land use/land cover change, and inflow from the Ili River) of the water conservation variation based on the linear regression, piecewise linear regression, and Pearson's correlation coefficient analyses. The results indicated that from 1975 to 2020, the water yield and water conservation in the IRD showed a decreasing trend, and the spatial distribution pattern was high in the east and low in the west; overall, the water conservation of all land use types decreased slightly. The water conservation volume of grassland was the most reduced, although the area of grassland increased owing to the increased inflow from the Ili River. At the same time, the increased inflow has led to the expansion of wetland areas, the improvement of vegetation growth, and the increase of regional evapotranspiration, thus resulting in an overall reduction in the water conservation. The water conservation depth and precipitation had similar spatial distribution patterns; the change in climate factors was the main reason for the decline in the water conservation function in the delta. The reservoir in the upper reaches of the IRD regulated runoff into the Lake Balkhash, promoted vegetation restoration, and had a positive effect on the water conservation; however, this positive effect cannot offset the negative effect of enhanced evapotranspiration. These results provide a reference for the rational allocation of water resources and ecosystem protection in the IRD.
分类： 地球科学 >> 地质学 提交时间： 2023-07-28
摘要： 【目的】本研究在2022年广西山口国家级红树林生态自然保护区（以下简称山口红树林保护区）实地调查数据的基础上，结合LUCC和景观格局指数，选取1987-2021期间六个时期的遥感影像，利用面向对象的图像分类方法，着重探索广西山口红树林湿地变化过程和重要影响因素。【结果】从土地利用角度来看：研究区近35年间地类之间不断转换，其中耕地面积持续减少，米草滩和养殖坑塘大比例增长，米草滩主要侵占原沿海滩涂，养殖坑塘主要由林地和耕地转换而来；就景观角度来看：景观破碎度持续增加，连通性逐渐降低，景观形状逐渐变得复杂，地类演替变得频繁；Pearson相关性分析表明，沿海滩涂、米草滩和养殖坑塘的土地利用变化与景观指数之间存在极显著或显著的相关性。【结论】在过去35年中，山口红树林保护区经历了重大的土地利用变化，入侵物种（米草滩）和人为干扰（养殖坑塘）是影响该地区红树林湿地变化的主要因素，也是景观破碎度持续增加的主要成因；研究采用多元方法，多角度分析，揭露区域影响因子的差异性，对典型红树林生态系统的环境管理和保护工作提供理论依据。
分类： 地球科学 >> 水文学 提交时间： 2023-05-30 合作期刊: 《干旱区研究》
摘要： 气候变化和人类活动是河川径流变化的主要驱动力。在相似气候的前提下，人类活动是流域径流变化的主导因素，定量识别人类活动对径流变化的作用机制对深入探究径流的变化特征具有重要意义。本研究以秦岭月河流域为研究对象，基于流域内水量平衡的基本原理，在相似气候的前提下，结合土地利用/覆被变化（LUCC）和归一化植被指数（NDVI）的变化，分析月河流域的径流变化来量化人类活动对径流的影响程度。结果表明：（1）19602018年流域内径流量的平均值为8.3108 m3,径流整体呈现出减少的趋势，变化趋势不显著。（2）在相似气候的前提下，本研究共得出6组气候相似年组，其中有3组年径流量增加，2组年径流量减少。（3）以第3组相似年组（2000年和2016年）为例来定量区分气候变化和人类活动对流域径流的影响，2016年与2000年相比，径流减少了4.7108 m3。（4）在第3组相似年组的时段内有25751.4 hm2的耕地转化为林地，林地面积增加了24998.9 hm2。（5）ND⁃VI的变化主要是由于人类活动所致，同一时段内NDVI增加的面积为242652.0 hm2，NDVI的变化趋势与径流量变化趋势相反。本研究可为分析人类活动对秦岭河川径流变化的影响提供理论依据。
分类： 地球科学 >> 地理学 提交时间： 2023-03-19 合作期刊: 《干旱区科学》
摘要：The impact of socioeconomic development on land-use and land-cover change (LUCC) in river basins varies spatially and temporally. Exploring the spatiotemporal evolutionary trends and drivers of LUCC under regional disparities is the basis for the sustainable development and management of basins. In this study, the Weihe River Basin (WRB) in China was selected as a typical basin, and the WRB was divided into the upstream of the Weihe River Basin (UWRB), the midstream of the Weihe River Basin (MWRB), the downstream of the Weihe River Basin (DWRB), the Jinghe River Basin (JRB), and the Luohe River Basin (LRB). Based on land-use data (cultivated land, forestland, grassland, built-up land, bare land, and water body) from 1985 to 2020, we analyzed the spatiotemporal heterogeneity of LUCC in the WRB using a land-use transfer matrix and a dynamic change model. The driving forces of LUCC in the WRB in different periods were detected using the GeoDetector, and the selected influencing factors included meteorological factors (precipitation and temperature), natural factors (elevation, slope, soil, and distance to rivers), social factors (distance to national highway, distance to railway, distance to provincial highway, and distance to expressway), and human activity factors (population density and gross domestic product (GDP)). The results indicated that the types and intensities of LUCC conversions showed considerable disparities across different sub-basins, where complex conversions among cultivated land, forestland, and grassland occurred in the LRB, JRB, and UWRB, with higher dynamic change before 2000. The conversion of other land-use types to built-up land was concentrated in the UWRB, MWRB, and DWRB, with substantial increases after 2000. Additionally, the driving effects of the influencing factors on LUCC in each sub-basin also exhibited distinct diversity, with the LRB and JRB being influenced by the meteorological and social factors, and the UWRB, MWRB, and DWRB being driven by human activity factors. Moreover, the interaction of these influencing factors indicated an enhanced effect on LUCC. This study confirmed the spatiotemporal heterogeneity effects of socioeconomic status on LUCC in the WRB under regional differences, contributing to the sustainable development of the whole basin by managing sub-basins according to local conditions.
分类： 地球科学 >> 地理学 提交时间： 2021-12-30 合作期刊: 《干旱区科学》
摘要： The Tarim River is the longest inland river in China and is considered as an important river to protect the oasis economy and environment of the Tarim Basin. However, excessive exploitation and over-utilization of natural resources, particularly water resources, have triggered a series of ecological and environmental problems, such as the reduction in the volume of water in the main river, deterioration of water quality, drying up of downstream rivers, degradation of vegetation, and land desertification. In this study, the land use/land cover change (LUCC) responses to ecological water conveyance in the lower reaches of the Tarim River were investigated using ENVI (Environment for Visualizing Images) and GIS (Geographic Information System) data analysis software for the period of 1990–2018. Multi-temporal remote sensing images and ecological water conveyance data from 1990 to 2018 were used. The results indicate that LUCC covered an area of 2644.34 km2 during this period, accounting for 15.79% of the total study area. From 1990 to 2018, wetland, farmland, forestland, and artificial surfaces increased by 533.42 km2 (216.77%), 446.68 km2 (123.66%), 284.55 km2 (5.67%), and 57.51 km2 (217.96%), respectively, whereas areas covered by grassland and other land use/land cover types, such as Gobi, bare soil, and deserts, decreased by 103.34 km2 (14.31%) and 1218.83 km2 (11.75%), respectively. Vegetation area decreased first and then increased, with the order of 2010<2000<1990<2018. LUCC in the overflow and stagnant areas in the lower reaches of the Tarim River was mainly characterized by fragmentation, irregularity, and complexity. By analyzing the LUCC responses to 19 rounds of ecological water conveyance in the lower reaches of the Tarim River from 2000 to the end of 2018, we proposed guidelines for the rational development and utilization of water and soil resources and formulation of strategies for the sustainable development of the lower reaches of the Tarim River. This study provides scientific guidance for optimal scheduling of water resources in the region.
分类： 地球科学 >> 地理学 提交时间： 2021-12-12 合作期刊: 《干旱区研究》
摘要： 以黄土高原中部的泾河流域为研究区，通过采用结合InVEST（Integrated Valuation of Ecosystem Servicesand Tradeoffs）模型生境质量与植被覆盖度的综合方法，分析植物多样性在栅格尺度上的时空变化，并结合灰色关联分析方法，分析植物多样性与土地利用强度、人口密度等因子的关联关系。结果表明：（1）泾河流域植物多样性处于中等水平（BS>0.53），空间格局变化明显。2000—2015年，流域内植物多样性平均值从0.5382增加到0.5951，其中，植物多样性高值区域占总面积的22.1%，主要分布在山地、国家自然保护区和林业地区，植物多样性低值区占总面积的5.99%，主要分布在城区及北部植被覆盖低区域。（2）土地利用强度是流域植物多样性的主要影响因素，其次太阳辐射和人口密度也会造成较大影响，此外还受其他因素的共同作用。
分类： 地球科学 >> 地理学 提交时间： 2019-06-20 合作期刊: 《干旱区科学》
摘要： The surface wind speed (SWS) is affected by both large-scale circulation and land use and cover change (LUCC). In China, most studies have considered the effect of large-scale circulation rather than LUCC on SWS. In this study, we evaluated the effects of LUCC on the SWS decrease during 1979–2015 over China using the observation minus reanalysis (OMR) method. There were two key findings: (1) Observed wind speed declined significantly at a rate of 0.0112 m/(s•a), whereas ERA-Interim, which can only capture the inter-annual variation of observed data, indicated a gentle downward trend. The effects of LUCC on SWS were distinct and caused a decrease of 0.0124 m/(s•a) in SWS; (2) Due to variations in the characteristics of land use types across different regions, the influence of LUCC on SWS also varied. The observed wind speed showed a rapid decline over cultivated land in Northwest China, as well as a decrease in China's northeastern and eastern plain regions due to the urbanization. However, in the Tibetan Plateau, the impact of LUCC on wind speed was only slight and can thus be ignored.
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